[SalesForce] Data Extension API: How to add record in data extension with no primary key via API call

Triggered Send Data Extensions are meant to be a log of API calls, not a primary source for subscriber data -- which is why Email Address and Subscriber Key cannot be primary keys.

With no primary key, there's nothing stopping multiple emails being triggered for a single subscriber. So unless you've added some other primary key (not recommended) or are utilizing an Exclusion Script), there will be duplicates in your TSD DE.

I'd suggest a single master Data Extension and a set of Queries in an Automation to take rows from your Triggered Send Data Extensions and upsert them into your master.

Or, as you mentioned, just upsert rows in your Data Extension directly from your page.

There is not a single option for this. Even the overwrite function inside of SQL is not truly a single operation. It is actually using 2 different operations behind the UI 'curtain'.

To do it via the API, you will first need to run a Delete Method on your DE (sample from SFMC Docs). You then will do an ADD Method on your DE to insert the new records (sample from SFMC Docs).

EDIT

Thanks to @SamWhitmore, there is an easier way than utilizing the DELETE METHOD, by Performing a Clear to the whole DE at once - similar to what is done via the UI. (https://developer.salesforce.com/docs/atlas.en-us.noversion.mc-apis.meta/mc-apis/clearing_data_from_a_data_extension.htm)

You can also do this via AMPScript if you add a 'reference column' to your DEs - I usually insert a column named 'Secret' and set it to a value of 1. This way you can always lookup or interact with all your columns by setting the 'WHERE' statement to Secret = 1.

You would then use the DeleteDE() and InsertDE() functions to 'Overwrite'.

This can also be done via SSJS the same way.